This invention relates to the precision dispensing of fluids, and more particularly to a face valve for use in the precision dispensing of fluids, such as for medical applications wherein precision, inert valving is required to control movement of fluids. For example, it may be used for dispensing fluids in an automatic medical analyzer such as diluents, liquid reagents, biological samples, etc.
Prior art valves for controlling the dispensing of fluid in medical applications have traditionally been of the type having a sliding, rotary motion. The so-called face valve with which the present invention is concerned has a valve member mounted for linear sliding movement across a face of the valve body. At least one pair of fluid passages extend through the valve body and terminate in open ends at its face. The valve member is movable between a first position in which the fluid passages are closed and a second position in which the fluid passages are interconnected by a channel in the valve member. A compression spring presses the valve member against the face of the valve body to maintain a tight seal.
Precision dispensing valves of this kind suitable for medical applications have been found to have an upredictable life. Particularly for medical applications, it is important that the materials used for the valve be inert to the fluids being dispensed. One proposed face valve for such application has utilized a graphite valve member acting on a ceramic valve body. The wear characteristics of this previous valve, however, were found to be unsatisfactory.
It is a purpose of this invention to provide an improved face valve for precision dispensing of fluids.
Further purposes include providing such a face valve which has a predictable life and improved wear characteristics.